5.1.1.1 : Abtract vector implementation

• 5.1.1.1.1) Implementation PAbstractVect3.h
• 5.1.1.1.2) Summary PAbstractVect3.h
• 5.1.1.1.3) Implementation PAbstractVect3_impl.h
• 5.1.1.1.4) Summary PAbstractVect3_impl.h

We will use the PAbstractVect3 class to use them as coordinate, velocity, acceleration of the Particle class.